A very elementary scheme to understand the meanings of simple sentences

There are 3 components - 

1. Definitions of non-small words (At, is, on, the etc. are the small words).
2. The Linguistic rules which the small words indicate.
3. The interconnections between the words.

E.g. - John is at home today.

        Lets see the 3 components -

1. Firstly, we should know the definitions of the non-small words John, Home and Today. John is a boy. A home is a place/structure for staying inside. Today is the present day.

2. 'Is' indicates being. ('X is' indicates the being of X). 'At' indicates the location of the subject. ('at X' indicates that the location of the subject is X).

3.  Look at things this way. We are just given words - 5 words - 1) John, 2) home, 3) at, 4) is & 5) today. The specific order is 14325 - John is at home today. 

Why do we write from left to right, one word after another? This brings with it a certain basic simpl principle in making sense of the connections between the words.

It is - Whenever there is a fragment A from the beginning (containing words w0 w1 w2 w3 …..wn-1), followed by a word ‘wn’, the linear left-to-right order indicates “it is (‘w0’ which is ‘w1’ which is ‘w2’....) which is ‘wn’ + remnant". 

Now, combine all the 3 components above. 

1. Firstly, John is a boy. Home is a place/structure for staying inside and today is the present day.
2. ‘Is’ is being. ‘At’ indicates location of the subject. 
3. Now lets apply the 3rd component along with the 1st 2. 

Fragment                       Meaning

John is :                        It is John which ‘is’ + at home today. 

John is at :                    It is John which is being, which is ‘at’ + home today.

John is at home :          It is John which is being, which is located at, which is ‘home’ +

today.

John is at home today : It is John which is being, which is located at, which is home, which is (on) this present day.

(NOTE :

• Every 'which' applies to the word just preceding it.
• The single-quoted words in the meanings of the fragments indicate that they are from the original sentence. Any repetition (for example, of is and at without the quotes indicates normal English usage of theirs; nothing to do with they being present in the original sentence). 

The above scheme provides a basic understanding of a simple sentence.